Conventional tube-bending machines or benders primarily employ compression, press and rotary draw methods to bend tubes along circular arcs. These machines and methods are commonly utilized in various industrial applications, including automobile and aircraft assembly, and equipment/conduit manufacture. These machines typically include a series of dies and a drive mechanism that cooperate to impart pressure upon a tube, so that the tube bends to a predetermined form. More particularly, with respect to rotary draw bending, a bend die is positioned adjacent the desired section of the tube. The tube is held in place and pressure is applied to the tube by clamping and pressure dies. A wiper die is further provided so that the tube conforms to the profile defined by the bend die with minimal deformation. To facilitate the production of a compound bend (i.e., a bend comprising multiple sections having differing radii and/or orientation), a stacked plurality of bend dies is often provided, wherein each die presents a different bending radius. In this configuration, the tube is shifted amongst the individual bend dies to effect the compound bend, thereby avoiding the need to disconnect the existing components, and connect new components to (i.e., change-over) the machine.
Where sequential singular or compound bends of differing radii, orientation or combinations thereof are desired, individual units of the bending tool set, including the bend, wiper, pressure, and/or clamping dies, must be replaced and/or repositioned, irrespective of a stacked configuration. The change-over period results in considerable down-time to the machine, as well as additional labor costs. In a repetitive environment, such as an assembly-line process, the costs associated with change-over periods present increasingly significant concerns; especially given that a typical change over of a complete tool set may take up to four hours of down-time per machine.
In automotive manufacturing, for example, change-over concerns are particularly presented by hydroform tube production, which utilizes conventional tube bending to effect pre-hydroform bends on dedicated single bend configuration lines. As hydroform technology is increasingly implemented on low and medium volume vehicles, the variety of bends encountered and bender use demands have likewise increased. As a result, the percentage of tube bending configurations that can be manufactured on one bender before requiring a complete tooling change has become increasingly limited.
To reduce costs associated with change-over, some bender manufacturers offer quick-change options for individual tooling details. Even with these provisions, however, significant change-over periods and labor costs persist. Accordingly, there remains a need in the art for an improved method of or apparatus for reducing the change-over period of bending machines, and otherwise increasing the flexibility of the bending process.